Semiconductor device

ABSTRACT

A multilayer semiconductor device includes first wirings extending in a first direction and arranged adjacent to each other in a second direction. Dummy wirings are arranged between the first wirings and the second wiring at crossing points between first virtual linear lines extending in a third direction and second virtual linear lines extending in a fourth direction. The third and fourth directions are neither parallel nor orthogonal to the first and second directions. The dummy wirings have a first, a second, and a third dummy wiring. Centers of the second and third dummy wirings are nearest to a center of the first dummy wiring relative to others of the dummy wirings. The respective centers of the first, second, and third dummy wirings are aligned on a third virtual linear line extending in a fifth direction neither parallel to nor perpendicular to the first and second directions.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present disclosure is a divisional of U.S. patent application Ser.No. 15/441,635 filed on Feb. 24, 2017, which is a divisional of U.S.patent application Ser. No. 15/242,885 filed on Aug. 22, 2016, now U.S.Pat. No. 9,978,737 issued May 22, 2018, which is a continuationapplication of U.S. patent application Ser. No. 14/613,824 filed Feb. 4,2015, now U.S. Pat. No. 9,455,223 issued Sep. 27, 2016, which is acontinuation application of U.S. application Ser. No. 14/136,692 filedDec. 20, 2013, now U.S. Pat. No. 8,984,466 issued Mar. 17, 2015, whichis a continuation application of U.S. application Ser. No. 13/795,573filed Mar. 12, 2013, now U.S. Pat. No. 8,637,950 issued Jan. 28, 2014,which is a continuation application of U.S. application Ser. No.13/485,165 filed May 31, 2012, now U.S. Pat. No. 8,418,114 issued Apr.9, 2013 which is a divisional application of U.S. application Ser. No.13/153,764 filed on Jun. 6, 2011, now U.S. Pat. No. 8,214,776 issuedJul. 3, 2012, which is a divisional application of U.S. Ser. No.12/857,065 filed on Aug. 16, 2010, now U.S. Pat. No. 7,977,233 issuedJul. 12, 2011 which is a divisional application of U.S. Ser. No.11/893,228 filed on Aug. 15, 2007, now U.S. Pat. No. 7,802,224 issuedSep. 21, 2010, which is a divisional application of U.S. Ser. No.10/999,290 filed on Nov. 29, 2004, now U.S. Pat. No. 7,271,490 issuedSep. 18, 2007, which is a continuation of U.S. Ser. No. 09/809,635 filedon Mar. 15, 2001, now U.S. Pat. No. 6,888,250 issued May 3, 2005,claiming priority to Japanese Application No. 2000-075671 filed Mar. 17,2000, all of which are hereby incorporated by reference in theirentireties.

BACKGROUND OF THE INVENTION 1. Field of the Invention

The present invention relates to a semiconductor device, a method formanufacturing the same, a method for generating mask data, a mask and acomputer readable recording medium, and more particularly to asemiconductor device having multiple wiring layers, a method formanufacturing the same, a method for generating mask data, a mask, acomputer readable recording medium.

2. Description of Related Art

Currently, multiple wiring layers are formed in order to realize highercircuit integration and further miniaturization of semiconductordevices. For example, multiple wiring layers are formed in the followingmanner. An interlayer dielectric layer is formed over a first wiringlayer, and the interlayer dielectric layer is polished by achemical-mechanical polishing method (hereinafter referred to as a “CMPmethod”). Then, a second wiring layer is formed over the interlayerdielectric layer, to thereby form multiple wiring layers.

As shown in FIG. 18, depending on a certain device design, first wiringlayers 130 a may be closely formed in one area and an isolated firstwiring layer 130 b may formed separated from such area on a firstinterlayer dielectric layer 120. Then, a second wiring layer 150 may beformed over the first wiring layers 130 a and 130 b through a secondinterlayer dielectric layer 140. In this case, the following problemsoccur.

When the second interlayer dielectric layer 140 is polished by a CMPmethod, a step difference is generated between an area of the secondinterlayer dielectric layer 140 where the first wiring layers 130 a areclosely formed and an area of the second interlayer dielectric layer 140where the isolated first wiring layer 130 b is formed. In other words,the area of the second interlayer dielectric layer 140 where theisolated first wiring layer 130 b is formed is excessively polishedcompared to the area of the second interlayer dielectric layer 140 wherethe first wiring layers 130 a are closely formed. This phenomenon occursbecause the polishing rate differs depending on pattern densities of thewiring layers. More particularly, a polishing pressure is concentratedon the area of the second interlayer dielectric layer 140 where theisolated first wiring layer 130 b is formed. As a result, the polishingrate of the second interlayer dielectric layer 140 in the area where theisolated first wiring layer 130 b is formed becomes greater than thepolishing rate of the second interlayer dielectric layer 140 in the areawhere the first wiring layers 130 a are closely formed. Consequently,the area of the second interlayer dielectric layer 140 in the area wherethe isolated first wiring layer 130 b is formed is excessively polished.

When the second interlayer dielectric layer 140 in the area where theisolated first wiring layer 130 b is formed is excessively polished,problems occur. For example, the thickness of the second interlayerdielectric layer 140 becomes irregular. When the thickness of the secondinterlayer dielectric layer 140 becomes irregular, a step difference isgenerated in the second wiring layer 150 that is formed over theinterlayer dielectric layer 140. When the step difference is generatedin the second wiring layer 150, problems occur. For example, when thesecond wiring layer 150 is patterned by a photolithography, a designedpattern is not optically focused depending on areas, and the pattern maynot be formed in such areas, or designed dimensions of the pattern maynot be obtained even if the pattern is formed.

In order to solve the problems described above, one technique isproposed. According to the technique, dummy wiring layers 132 are formedin an area between the area where the first wiring layers 130 a aredensely formed and the area where the isolated first wiring layer 130 bis formed, as shown in FIG. 19.

The technique for forming such dummy wiring layers is described inJapanese laid-open patent application HEI 4-218918, Japanese laid-openpatent application HEI 10-335333, U.S. Pat. Nos. 4,916,514, 5,556,805,5,597,668, 5,790,417 and 5,798,298.

SUMMARY OF THE INVENTION

It is an object of the present invention to provide a semiconductordevice in which dummy wiring layers are formed in a specified pattern, amethod for manufacturing the same, a method for generating mask data, amask, and a computer readable recording medium.

(A) In accordance with a first embodiment of the present invention, asemiconductor device comprises: a first wiring layer defining a rowdirection and first virtual linear lines extending in a direction thattraverses the row direction; and a plurality of dummy wiring layersprovided in the same level as the first wiring layer, wherein the rowdirection and the first virtual linear lines define an angle of 2 to 40degrees, and the plurality of dummy wiring layers are disposed on thefirst virtual linear lines.

The “row direction” used here refers to one direction that is virtuallydefined in consideration of, for example, a restriction region.

In the semiconductor device in accordance with the first embodiment ofthe present invention, the dummy wiring layers are disposed on the firstvirtual linear lines. The row direction and the first virtual linearlines define an angle between 2 degrees and 40 degrees. In other words,adjacent ones of the dummy wiring layers that are formed on the firstvirtual linear lines and disposed in the row direction are mutuallyoffset in a column direction. As a result, the dummy wiring layers canbe densely formed in an area adjacent to a restriction region thatextends in the row direction. In other words, even when some of thedummy wiring layers overlap the restriction region, the other dummywiring layers are securely disposed in an area adjacent to therestriction region. As a consequence, when a dielectric layer formedover the first wiring layer is polished, the polishing pressure can besecurely distributed over the dummy wiring layers even in an areaadjacent to the restriction region.

Moreover, since the dummy wiring layers can be securely provided in aregion adjacent to the restriction region, the dummy wiring layers canbe securely disposed in an area where a separation between adjacent onesof the first wiring layers is narrow.

In the semiconductor device in accordance with the first embodiment ofthe present invention, the first virtual linear lines may preferably bespaced a specified gap from one another. The gap may preferably be 1-16μm.

A center of each of the dummy wiring layers may preferably be located oneach of the first virtual linear lines.

(B) In accordance with a second embodiment of the present invention, asemiconductor device comprises: a first wiring layer defining a columndirection and second virtual linear lines extending in a direction thattraverses the column direction; and a plurality of dummy wiring layersprovided in the same level as the first wiring layer, wherein the columndirection and the second virtual linear lines define an angle of 2 to 40degrees, and the plurality of dummy wiring layers are disposed on thesecond virtual linear lines.

The “column direction” used here refers to one direction thatperpendicularly traverses the row direction and is virtually defined inconsideration of, for example, a restriction region.

In the semiconductor device in accordance with the second embodiment ofthe present invention, the dummy wiring layers are disposed on thesecond virtual linear lines. The column direction and the second virtuallinear lines define an angle between 2 degrees and 40 degrees. In otherwords, adjacent ones of the dummy wiring layers that are formed on thesecond virtual linear lines and disposed in the column direction aremutually offset in the row direction. As a result, the dummy wiringlayers in high density can be readily formed in an area adjacent to arestriction region that extends in the column direction. In other words,even when some of the dummy wiring layers overlap the restrictionregion, the other dummy wiring layers are securely disposed in an areaadjacent to the restriction region. As a consequence, when a dielectriclayer formed over the first wiring layer is polished, the polishingpressure can be securely distributed over the dummy wiring layers evenin an area adjacent to the restriction region.

Moreover, since the dummy wiring layers can be securely provided in aregion adjacent to the restriction region, the dummy wiring layers canbe securely disposed in a narrow area between two adjacent ones of thefirst wiring layers.

Also, the semiconductor device in accordance with the first embodimentand the semiconductor device in accordance with the second embodimentmay be combined. By the semiconductor device in accordance with thecombined embodiments, the dummy wiring layers can be more securelyformed in areas adjacent to restriction regions.

In the semiconductor device in accordance with the second embodiment ofthe present invention, the second virtual linear lines may preferably bespaced a specified gap from one another. The gap may preferably be 1-16μm.

A center of each of the dummy wiring layers may preferably be located oneach of the second virtual linear lines.

In the semiconductor device in accordance with the first embodiment orthe second embodiment, the dummy wiring layers may be formed in any oneof the following manners:

(1) A plan area of the dummy wiring layers is 30-50% of a unit planarea. As a result, the polishing pressure can be more effectivelydistributed on the dummy wiring layers. In a preferred embodiment, theplan area of the dummy wiring layers may be about 40% of the unit planarea.

(2) Each of the dummy wiring layers may have a generally rectangularshape in plan view. In other words, when the silicon substrate is viewedfrom above, each of the dummy wiring layers may have a generallyrectangular shape. The formation of a dummy wiring layer in a generallyrectangular shape is relatively easy. Preferably, each of the dummywiring layers may have a generally square shape. By forming the dummywiring layers in a generally square shape, the dummy wiring layers canbe more densely formed. For example, the dummy wiring layers can be moresecurely formed in an area adjacent to a cross section where restrictionregions cross one another. As a result, the dummy wiring layers can bemore effectively formed in an area adjacent to a restriction region witha complex pattern (for example, a prohibited area around a first wiringlayer that is formed with a complex pattern).

(3) When each of the dummy wiring layers has a rectangular shape in planview (i.e., as viewed from above), adjacent ones of the dummy wiringlayers disposed on the first virtual linear line or adjacent ones of thedummy wiring layers disposed on the second virtual linear line havesides that partially oppose to one another as viewed from above. In apreferred embodiment, the sides of the adjacent ones of the dummy wiringlayers are spaced a distance from one another, wherein the distance maypreferably be shorter than each of the sides of each of the dummy wiringlayers. Preferably, the distance between the opposing sides may be 0.5-5μm. More preferably, the distance between the opposing sides may beabout 1 μm.

(4) When the plan configuration of each of the dummy wiring layers isrectangular, each side of each of the dummy wiring layers may preferablyhave a length of about 1 μm or greater. When each side of each of thedummy wiring layers is about 1 μm long or greater, the amount of datafor generating masks which is used to form the dummy wiring layers isprevented from increasing.

In a preferred embodiment, each side of each of the dummy wiring layersis about 10 μm long or shorter. It is noted that a step difference ismore likely generated when a separation between adjacent wiring layersis greater than 10 μm. Therefore, when each side of each of the dummywiring layers is 10 μm long or shorter, the dummy wiring layers can beformed in a space where the adjacent wiring layers are separated fromone another by a distance greater than 10 μm. Accordingly, stepdifferences in an interlayer dielectric layer can be more effectivelyeliminated. In a preferred embodiment, the each side of each of thedummy wiring layers has a length of about 2 μm.

(C) In accordance with a third embodiment of the present invention, asemiconductor device comprises: a first wiring layer defining a rowdirection and a column direction; and a plurality of dummy wiring layersprovided in the same level as the first wiring layer, wherein each ofthe dummy wiring layers has a generally square shape in plan, adjacentones of the dummy wiring layers that are disposed in the row directionare spaced a first distance from one another, the first distance beingabout a half of a side of each of the dummy wiring layers, and theadjacent ones of the dummy wiring layers that are disposed in the rowdirection are offset by a second distance from one another in the columndirection, the second distance being about a half of a side of each ofthe dummy wiring layers.

The “row direction” and the “column direction” may be defined in asimilar manner as the first and second embodiments.

In accordance with the third embodiment of the present invention, theadjacent dummy wiring layers disposed in the row direction are mutuallyoffset in the column direction. As a result, the semiconductor device inaccordance with the third embodiment of the present invention providesthe same effects achieved by the semiconductor device in accordance withthe first embodiment of the present invention.

(D) In accordance with a fourth embodiment of the present invention, asemiconductor device comprises: a first wiring layer defining a rowdirection and a column direction; and a plurality of dummy wiring layersprovided in the same level as the first wiring layer, wherein each ofthe dummy wiring layers has a generally square shape in plan, adjacentones of the dummy wiring layers that are disposed in the columndirection are spaced a first distance from one another, the firstdistance being about a half of a side of each of the dummy wiringlayers, and the adjacent ones of the dummy wiring layers that aredisposed in the column direction are offset by a second distance fromone another in the row direction, the second distance being about a halfof a side of each of the dummy wiring layers.

The “row direction” and the “column direction” may be defined in asimilar manner as the first and second embodiments.

In accordance with the fourth embodiment of the present invention, theadjacent dummy wiring layers disposed in the column direction aremutually offset in the row direction. As a result, the semiconductordevice in accordance with the fourth embodiment of the present inventionprovides the same effects achieved by the semiconductor device inaccordance with the second embodiment of the present invention.

Also, the semiconductor device in accordance with the third embodimentand the semiconductor device in accordance with the fourth embodimentmay be combined. By the semiconductor device in accordance with thecombined embodiments, the dummy wiring layers can be more securelyformed in areas adjacent to restriction regions.

In the semiconductor device in accordance with the third embodiment orthe fourth embodiment, each side of each of the dummy wiring layers maypreferably have a length of about 2 μm.

The semiconductor device in accordance with any one of the firstembodiment through the fourth embodiment may preferably have at leastone restriction region, wherein the dummy wiring layers that would atleast partially overlap the at least one restriction region are notformed at all. As a result, pattern skipping in the pattern for thedummy wiring layers is securely prevented. In one embodiment, therestriction region may include a wiring effective region and aprohibited area provided around the wiring effective region.

The wiring effective region may include, for example, a region where thefirst wiring layer is formed. Also, the semiconductor device may includea second wiring layer formed at a level above the first wiring layer anda third wiring layer formed at a level below the first wiring layer. Inthis case, the wiring effective region may preferably include a regionwhere a contact hole is formed that connects the second wiring layer andthe third wiring layer. For example, the third wiring layer may be adiffusion layer formed in a semiconductor substrate, a wiring layerformed over a surface of a semiconductor substrate, or a wiring layerformed over an interlayer dielectric layer.

The width of the prohibited area is determined in consideration ofcircuit design. For example, the prohibited area has a width of 0.5-100μm. When a semiconductor device does not use circuits that useelectromagnetic effects, for example, inductors using wiring layers, theprohibited area may preferably have a width of 0.5-20 μm. It is notedthat the width of the prohibited area may or may not be the same alongthe entire prohibited area.

(E) In accordance with a fifth embodiment of the present invention, amethod is provided for manufacturing a semiconductor device. The methodcomprises forming a first wiring layer defining a row direction andfirst virtual linear lines extending in a direction that traverses therow direction, and forming a plurality of dummy wiring layers, whereinthe row direction and the first virtual linear lines define an angle of2-40 degrees, and the plurality of dummy wiring layers are disposed onthe first virtual linear lines.

In accordance with the fifth embodiment of the present invention, thedummy wiring layers are formed in the step of forming the first wiringlayer. The dummy wiring layers are formed in the same pattern as thepattern described above in conjunction with the semiconductor device ofthe first embodiment of the present invention. As a result, the dummywiring layers can be securely formed in an area adjacent to arestriction region. As a consequence, when a dielectric layer formedover the first wiring layer is polished, the polishing pressure can besecurely distributed over the dummy wiring layers. Accordingly, theinterlayer dielectric layer obtained after the polishing step can have auniform thickness.

(F) A method for manufacturing a semiconductor device in accordance witha sixth embodiment of the present invention comprises forming a firstwiring layer defining a column direction and second virtual linear linesextending in a direction that traverses the column direction, andforming a plurality of dummy wiring layers, wherein the column directionand the second virtual linear lines define an angle of 2-40 degrees, andthe plurality of dummy wiring layers are disposed on the second virtuallinear lines.

In accordance with the sixth embodiment of the present invention, thedummy wiring layers are formed in the same pattern as the patterndescribed above in conjunction with the semiconductor device of thesecond embodiment of the present invention. As a result, the sixthembodiment of the present invention can provide the same effects thatare achieved by the method for manufacturing a semiconductor device inaccordance with the fifth embodiment of the present invention.

Also, the method for manufacturing a semiconductor device in accordancewith the fifth embodiment and the method for manufacturing asemiconductor device in accordance with the sixth embodiment may becombined.

By the method for manufacturing a semiconductor device in accordancewith the combined embodiments, dummy wiring layers can be more securelyformed in areas adjacent to restriction regions. Accordingly, theinterlayer dielectric layer obtained after the polishing step can have amore uniform thickness.

The features of the first and second virtual linear lines describedabove in connection with the semiconductor devices are applicable to thefifth and sixth embodiments of the present invention. Also, the dummywiring layers can be formed in manners similar to the first throughfourth embodiments described above in connection with the semiconductordevices.

(G) A method for manufacturing a semiconductor device in accordance witha seventh embodiment of the present invention comprises forming a firstwiring layer defining a row direction and a column direction and aplurality of dummy wiring layers, wherein each of the dummy wiringlayers has a generally square shape in plan view, adjacent ones of thedummy wiring layers that are disposed in the row direction are spaced afirst distance from one another, the first distance being about a halfof a side of each of the dummy wiring layers, and the adjacent ones ofthe dummy wiring layers that are disposed in the row direction areoffset by a second distance from one another in the column direction,the second distance being about a half of a side of each of the dummywiring layers.

In accordance with the seventh embodiment of the present invention, thedummy wiring layers are formed in the same pattern as the patterndescribed above in conjunction with the semiconductor device of thethird embodiment of the present invention. As a result, the seventhembodiment of the present invention can provide the same effects thatare achieved by the method for manufacturing a semiconductor device inaccordance with the fifth embodiment of the present invention.

(H) A method for manufacturing a semiconductor device in accordance withan eighth embodiment of the present invention comprises forming a firstwiring layer defining a row direction and a column direction and aplurality of dummy wiring layers, wherein each of the dummy wiringlayers has a generally square shape in plan view, adjacent ones of thedummy wiring layers that are disposed in the column direction are spaceda first distance from one another, the first distance being about a halfof a side of each of the dummy wiring layers, and the adjacent ones ofthe dummy wiring layers that are disposed in the column direction areoffset by a second distance from one another in the row direction, thesecond distance being about a half of a side of each of the dummy wiringlayers.

In accordance with the eighth embodiment of the present invention, thedummy wiring layers are formed in the same pattern as the patterndescribed above in conjunction with the semiconductor device of thefourth embodiment of the present invention. As a result, the eighthembodiment of the present invention can provide the same effects thatare achieved by the method for manufacturing a semiconductor device inaccordance with the fifth embodiment of the present invention.

Also, the method for manufacturing a semiconductor device in accordancewith the seventh embodiment and the method for manufacturing asemiconductor device in accordance with the eighth embodiment may becombined.

By the method for manufacturing a semiconductor device in accordancewith the combined embodiments, the dummy wiring layers can be moresecurely formed in areas adjacent to restriction regions. Accordingly,the interlayer dielectric layer obtained after the polishing step canhave a more uniform thickness.

In one embodiment, the restriction region may have the same features asdescribed above in connection with the semiconductor devices.

(I) In accordance with a ninth embodiment of the present invention, amethod is provided for generating mask data that is used formanufacturing a semiconductor device. The method comprises the steps of:

(a) setting a restriction region pattern that defines the restrictionregion;

(b) setting dummy patterns that define the dummy wiring layers; and

(c) mixing the restriction region pattern and the dummy patterns,wherein the dummy patterns that at least partially overlap therestriction region pattern are entirely excluded.

In accordance with the ninth embodiment of the present invention, forexample, the following two effects are achieved.

(1) The dummy patterns define dummy wiring layers. Accordingly, thedummy patterns include patterns corresponding to placement patterns ofthe dummy wiring layers. As a result, in step (c), the dummy patterns inhigh density can be readily set in an area adjacent to a restrictionregion pattern. In other words, even when some of the dummy patternsoverlap the restriction region pattern, the other dummy patterns aresecurely generated in an area adjacent to the restriction regionpattern. As a consequence, dummy patterns can be securely set in regionsadjacent to restriction region patterns. As a result, the followingeffects are achieved.

When dummy wiring layers are formed, the dummy wiring layers can besecurely disposed in an area adjacent to the restriction regions. As aconsequence, when a dielectric layer formed over the wiring layer ispolished, the polishing pressure is securely distributed on the dummywiring layers in areas adjacent to the restriction regions. As a result,an interlayer dielectric layer formed in areas adjacent to therestriction regions and in other areas over the wiring layers can have auniform thickness.

Moreover, since the dummy patterns can be securely provided in areasadjacent to the restriction regions, the dummy patterns can be securelydisposed in an area where a separation between adjacent restrictionregion patterns is narrow.

(2) Also, in accordance with the present invention, the dummy patternsthat at least partially overlap the restriction region pattern areentirely excluded. As a result, pattern skipping of patterns of thedummy wiring layers can be securely prevented, as described below indetail.

(J) In accordance with a tenth embodiment of the present invention, amethod is provided for generating mask data that is used for a methodfor manufacturing a semiconductor device. The semiconductor devicecomprises a first wiring layer and a plurality of dummy wiring layersprovided in the same level as the first wiring layer. Placement of theplurality of dummy wiring layers is determined by a method including thesteps of:

(a) setting a restriction region pattern that defines a restrictionregion;

(b) setting dummy patterns that define the dummy wiring layers, anddefining a row direction and first virtual linear lines extending in adirection that traverses the row direction, wherein the row directionand the first virtual linear lines define an angle of 2-40 degrees, andthe dummy wiring layers are disposed on the first virtual linear lines;and

(c) mixing the restriction region pattern and the dummy patterns,wherein the dummy patterns that at least partially overlap therestriction region pattern are entirely excluded.

The “row direction” used here refers to one direction that is virtuallydefined in consideration of, for example, a restriction region.

In accordance with the tenth embodiment of the present invention, thedummy patterns are formed in a manner to be disposed on the firstvirtual linear lines. The row direction and the first virtual linearlines define an angle of 2 to 40 degrees. In other words, adjacent onesof the dummy patterns that are formed on the first virtual linear linesand disposed next to each other in the row direction are mutually offsetin a column direction. As a result, the dummy patterns with high densitycan be readily disposed in areas adjacent to restriction region patternsthat extend in the row direction. In other words, even when some of thedummy patterns overlap the restriction region patterns, the other dummypatterns are securely disposed in the areas adjacent to the restrictionregion patterns. As a consequence, the tenth embodiment can provide theeffect (1) achieved by the method for generating mask data of the ninthembodiment.

Also, the tenth embodiment can provide the effect (2) achieved by themethod for generating mask data of the ninth embodiment.

(K) In accordance with an eleventh embodiment of the present invention,a method is provided for generating mask data that is used for a methodfor manufacturing a semiconductor device. The semiconductor devicecomprises a first wiring layer and a plurality of dummy wiring layersprovided in the same level as the first wiring layer. Placement of theplurality of dummy wiring layers is determined by a method including thesteps of:

(a) setting a restriction region pattern that defines a restrictionregion;

(b) setting dummy patterns that define the dummy wiring layers, anddefining a column direction and second virtual linear lines extending ina direction that traverses the column direction, wherein the columndirection and the second virtual linear lines define an angle of 2-40degrees, and the dummy wiring layers are disposed on the second virtuallinear lines; and

(c) mixing the restriction region pattern and the dummy patterns,wherein the dummy patterns that at least partially overlap therestriction region pattern are entirely excluded.

The “column direction” used here refers to one direction thatperpendicularly traverses the row direction and is virtually defined inconsideration of, for example, a restriction region.

In accordance with the eleventh embodiment of the present invention, thedummy patterns are formed in a manner to be disposed on the secondvirtual linear lines. The column direction and the second virtual linearlines define an angle of 2 to 40 degrees. In other words, adjacent onesof the dummy patterns that are formed on the second virtual linear linesand disposed next to each other in the column direction are mutuallyoffset in the row direction. As a result, the dummy patterns with highdensity can be readily disposed in areas adjacent to restriction regionpatterns that extend in the column direction. In other words, even whensome of the dummy patterns overlap the restriction region patterns, theother dummy patterns are securely disposed in areas adjacent to therestriction region patterns. As a consequence, the eleventh embodimentcan provide the effect (1) achieved by the method for generating maskdata of the ninth embodiment.

Also, the eleventh embodiment can provide the effect (2) achieved by themethod for generating mask data of the ninth embodiment.

Also, the method for generating mask data in accordance with the tenthembodiment and the method for generating mask data in accordance withthe eleventh embodiment may be combined. By the method for generatingmask data in accordance with the combined embodiments, dummy patternscan be more securely formed in areas adjacent to restriction regions.

(L) In accordance with a twelfth embodiment of the present invention, amethod is provided for generating mask data that is used for a methodfor manufacturing a semiconductor device. The semiconductor devicecomprises a first wiring layer defining a row direction and a columndirection and a plurality of dummy wiring layers provided in anidentical level as the first wiring layer, wherein placement of theplurality of dummy wiring layers is determined by a method including thesteps of:

(a) setting a restriction region pattern that defines a restrictionregion;

(b) setting dummy patterns that define the dummy wiring layers, whereineach of the dummy wiring layers has a generally square shape in planview, adjacent ones of the dummy wiring layers that are disposed in therow direction are spaced a first distance from one another, the firstdistance being about a half of a side of each of the dummy wiringlayers, and the adjacent ones of the dummy wiring layers that aredisposed in the row direction are offset by a second distance from oneanother in the column direction, the second distance being about a halfof a side of each of the dummy wiring layers; and

(c) mixing the restriction region pattern and the dummy patterns,wherein the dummy patterns that at least partially overlap therestriction region pattern are entirely excluded.

The “row direction” and the “column direction” may be defined in asimilar manner as the tenth and eleventh embodiments.

In the method for generating mask data in accordance with the twelfthembodiment of the present invention, the adjacent dummy patternsdisposed next to one another in the row direction are mutually offset inthe column direction. As a result, the method for generating mask datain accordance with the twelfth embodiment of the present inventionprovides the same effects achieved by the method for generating maskdata in accordance with the tenth embodiment of the present invention.

(M) In accordance with a thirteenth embodiment of the present invention,a method is provided for generating mask data that is used for a methodfor manufacturing a semiconductor device. The semiconductor devicecomprises a first wiring layer defining a row direction and a columndirection and a plurality of dummy wiring layers provided in the samelevel as the first wiring layer, wherein placement of the plurality ofdummy wiring layers is determined by a method including the steps of:

(a) setting a restriction region pattern that defines a restrictionregion;

(b) setting dummy patterns that define the dummy wiring layers, whereineach of the dummy wiring layers has a generally square shape in plan,adjacent ones of the dummy wiring layers that are disposed in the columndirection are spaced a first distance from one another, the firstdistance being about a half of a side of each of the dummy wiringlayers, and the adjacent ones of the dummy wiring layers that aredisposed in the column direction are offset by a second distance fromone another in the row direction, the second distance being about a halfof a side of each of the dummy wiring layers; and

(c) mixing the restriction region pattern and the dummy patterns,wherein the dummy patterns that at least partially overlap therestriction region pattern are entirely excluded.

The “row direction” and the “column direction” may be defined in asimilar manner as the tenth and eleventh embodiments.

In the method for generating mask data in accordance with the thirteenthembodiment of the present invention, the adjacent dummy patternsdisposed next to one another in the column direction are mutually offsetin the row direction. As a result, the method for generating mask datain accordance with the thirteenth embodiment of the present inventionprovides the same effects achieved by the method for generating maskdata in accordance with the eleventh embodiment of the presentinvention.

Also, the method for generating mask data in accordance with the twelfthembodiment and the method for generating mask data in accordance withthe thirteenth embodiment may be combined. By the method for generatingmask data in accordance with the combined embodiments, dummy patternscan be more securely formed in areas adjacent to restriction regions.

The method for generating mask data in accordance with any one of thetenth embodiment through the thirteenth embodiment may have any one ofthe following embodiments:

The restriction region includes a wiring effective region and aprohibited area provided around the wiring effective region, and thestep (a) includes the steps of: (a-1) setting a wiring effective regionpattern that defines the wiring effective region and (a-2) setting aprohibited area pattern that defines the prohibited area about thewiring effective region pattern.

The wiring effective region pattern may include a wiring pattern.

When the semiconductor device includes a second wiring layer formed at alevel above the first wiring layer and a third wiring layer formed at alevel below the first wiring layer, and a contact hole for connectingthe second wiring layer and the third wiring layer is formed, the wiringeffective region pattern may preferably include a contact hole patternfor connecting the second wiring layer and the third wiring layer.

(N) In accordance with a fourteenth embodiment of the present invention,a method is provided for generating mask data that is used for a methodfor manufacturing a semiconductor device. The semiconductor devicecomprises a first wiring layer defining a row direction and firstvirtual linear lines extending in a direction that traverses the rowdirection and a plurality of dummy wiring layers provided in the samelevel as the first wiring layer, wherein the row direction and the firstvirtual linear lines define an angle of 2-40 degrees, and the pluralityof dummy wiring layers are disposed to be located on the first virtuallinear lines. The method comprises the steps of:

(a) setting a restriction region pattern that defines a restrictionregion;

(b) setting dummy patterns that define the dummy wiring layers; and

(c) mixing the restriction region pattern and the dummy patterns,wherein the dummy patterns that at least partially overlap therestriction region pattern are entirely excluded.

The “row direction” may be defined in a similar manner as the tenthembodiment.

In accordance with the fourteenth embodiment of the present invention,for example, the following two effects are achieved.

(1) In accordance with the fourteenth embodiment of the presentinvention, the dummy patterns are set such that the dummy wiring layersare disposed on the first virtual linear lines. The row direction andthe first virtual linear lines define an angle of 2 to 40 degrees. Inother words, the dummy patterns are set such that adjacent ones of thedummy wiring layers formed on the first virtual linear lines anddisposed next to one another in the row direction are mutually offset ina column direction. Accordingly, the adjacent dummy patterns disposednext to one another in the row direction are mutually offset in thecolumn direction. As a result, in step (c), the dummy patterns can bereadily set with high density in an area adjacent to a restrictionregion pattern that extends in the row direction. In other words, evenwhen some of the dummy patterns overlap the restriction region pattern,the other dummy patterns are securely generated in an area adjacent tothe restriction region pattern. As a consequence, dummy patterns can besecurely provided in a region where a gap between adjacent restrictionregion patterns is narrow. As a result, the following effects areachieved.

When dummy wiring layers are formed, the dummy wiring layers can besecurely disposed in an area adjacent to the restriction regions. As aconsequence, when a dielectric layer formed over the first wiring layeris polished, the polishing pressure is securely distributed on the dummywiring layers in areas adjacent to the restriction regions.

(2) Also, in accordance with the fourteenth embodiment of the presentinvention, the dummy patterns that at least partially overlap therestriction region pattern are entirely excluded. As a result, thegeneration of pattern skipping of patterns of dummy wiring layers can besecurely prevented, as described below in detail.

(O) In accordance with a fifteenth embodiment of the present invention,a method is provided for generating mask data that is used for a methodfor manufacturing a semiconductor device. The semiconductor devicecomprises a first wiring layer defining a column direction and secondvirtual linear lines extending in a direction that traverses the columndirection and a plurality of dummy wiring layers provided in the samelevel as the second wiring layer, wherein the column direction and thesecond virtual linear lines define an angle of 2-40 degrees, and theplurality of dummy wiring layers are located on the second virtuallinear lines. The method comprises the steps of:

(a) setting a restriction region pattern that defines a restrictionregion;

(b) setting dummy patterns that define the dummy wiring layers; and

(c) mixing the restriction region pattern and the dummy patterns,wherein the dummy patterns that at least partially overlap therestriction region pattern are entirely excluded.

The “column direction” may be defined in a similar manner as theeleventh embodiment.

In accordance with the fifteenth embodiment of the present invention,for example, the following two effects are achieved.

(1) In accordance with the fifteenth embodiment of the presentinvention, the dummy patterns are set such that the dummy wiring layersare disposed to be located on the second virtual linear lines. Thecolumn direction and the second virtual linear lines define an angle of2 to 40 degrees. In other words, the dummy patterns are set such thatadjacent ones of the dummy wiring layers formed on the second virtuallinear lines and disposed next to one another in the column directionare mutually offset in the row direction. Accordingly, the adjacentdummy patterns disposed next to one another in the column direction aremutually offset in the row direction. As a result, in step (c), thedummy patterns can be readily set with high density in an area adjacentto a restriction region pattern that extends in the column direction. Inother words, even when some of the dummy patterns overlap therestriction region pattern, the other dummy patterns are securelygenerated in an area adjacent to the restriction region pattern. As aconsequence, dummy patterns can be securely provided in a region where aseparation between adjacent restriction region patterns is narrow. As aresult, the effect (1) described above in conjunction with the methodfor generating mask data of the fourteenth embodiment can be achieved.

(2) In accordance with the fifteenth embodiment of the presentinvention, the dummy patterns that at least partially overlap therestriction region pattern are entirely excluded. As a result, theeffect (2) described above in conjunction with the method for generatingmask data of the fourteenth embodiment can be achieved.

Also, the method for generating mask data in accordance with thefourteenth embodiment and the method for generating mask data inaccordance with the fifteenth embodiment may be combined. By the methodfor generating mask data in accordance with the combined embodiments,dummy wiring layers can be more securely formed in areas adjacent torestriction regions.

(P) In accordance with a sixteenth embodiment of the present invention,a method is provided for generating mask data that is used for a methodfor manufacturing a semiconductor device. The semiconductor devicecomprises a first wiring layer defining a row direction and a columndirection and a plurality of dummy wiring layers provided in the samelevel as the first wiring layer, wherein each of the dummy wiring layershas a generally square shape in plan view, adjacent ones of the dummywiring layers that are disposed next to one another in the row directionare spaced a first distance from one another, the first distance beingabout a half of a side of each of the dummy wiring layers, and theadjacent ones of the dummy wiring layers that are disposed next to oneanother in the row direction are offset by a second distance from oneanother in the column direction, the second distance being about a halfof a side of each of the dummy wiring layers, and the method comprisesthe steps of:

(a) setting a restriction region pattern that defines a restrictionregion;

(b) setting dummy patterns that define the dummy wiring layers; and

(c) mixing the restriction region pattern and the dummy patterns,wherein the dummy patterns that at least partially overlap therestriction region pattern are entirely excluded.

The “row direction” and the “column direction” may be defined in asimilar manner as the tenth and eleventh embodiments.

In the method for generating mask data in accordance with the sixteenthembodiment of the present invention, the adjacent dummy patternsdisposed next to one another in the row direction are mutually offset inthe column direction. As a result, the method for generating mask datain accordance with the sixteenth embodiment of the present inventionprovides the same effects achieved by the method for generating maskdata in accordance with the fourteenth embodiment of the presentinvention.

(Q) In accordance with a seventeenth embodiment of the presentinvention, a method is provided for generating mask data that is usedfor a method for manufacturing a semiconductor device. The semiconductordevice comprises a first wiring layer defining a row direction and acolumn direction and a plurality of dummy wiring layers provided in thesame level as the first wiring layer, wherein each of the dummy wiringlayers has a generally square shape in plan view, adjacent ones of thedummy wiring layers that are disposed next to one another in the columndirection are spaced a first distance from one another, the firstdistance being about a half of a side of each of the dummy wiringlayers, and the adjacent ones of the dummy wiring layers that aredisposed in the column direction are offset by a second distance fromone another in the row direction, the second distance being about a halfof a side of each of the dummy wiring layers, and the method comprisesthe steps of:

(a) setting a restriction region pattern that defines a restrictionregion;

(b) setting dummy patterns that define the dummy wiring layers; and

(c) mixing the restriction region pattern and the dummy patterns,wherein the dummy patterns that at least partially overlap therestriction region pattern are entirely excluded.

The “row direction” and the “column direction” may be defined in asimilar manner as the tenth and eleventh embodiments.

In the method for generating mask data in accordance with theseventeenth embodiment of the present invention, the adjacent dummypatterns disposed next to one another in the column direction aremutually offset in the row direction. As a result, the method forgenerating mask data in accordance with the seventeenth embodiment ofthe present invention provides the same effects achieved by the methodfor generating mask data in accordance with the fifteenth embodiment ofthe present invention.

Also, the method for generating mask data in accordance with thesixteenth embodiment and the method for generating mask data inaccordance with the seventeenth embodiment may be combined. By themethod for generating mask data in accordance with the combinedembodiments, the dummy wiring layers can be more securely formed inareas adjacent to restriction regions.

The restriction region may have the same features as described above inconnection with the semiconductor devices. Also, the wiring effectiveregion may have the same features as described above in connection withthe semiconductor devices.

The method for generating mask data in accordance with any one of theninth through seventeenth embodiments may further include, before step(c), step (d) of reversing the restriction region pattern. By theinclusion of step (d), the restriction region pattern and the dummypatterns can be easily mixed.

A mask in accordance with one embodiment of the present invention can beformed by the method for generating mask data described above.

By the use of the mask in accordance with the present invention in amethod for manufacturing a semiconductor device, dummy wiring layers canbe securely formed in areas adjacent to restriction regions.

A computer readable recording medium in accordance with the presentinvention stores mask data obtained by the method for generating maskdata according to any one of the embodiments described above.

A mask of the present invention can be formed based on the data storedin the computer readable recording medium in accordance with the presentinvention.

Other features and advantages of the invention will be apparent from thefollowing detailed description, taken in conjunction with theaccompanying drawings that illustrate, by way of example, variousfeatures of embodiments of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 schematically shows a plan view of a semiconductor device.

FIG. 2 schematically shows a cross-sectional view taken along a line A-Aof FIG. 1.

FIG. 3 shows a plan view of a surface at a level where first wiringlayers are formed.

FIG. 4 schematically shows a plan view of patterns of dummy wiringlayers.

FIGS. 5 (a) and 5 (b) schematically show plan view of patterns of dummywiring layers adjacent to prohibited areas.

FIGS. 6 (a) and 6 (b) show intermediate mask data representing patternsused in a process for forming first mask data.

FIG. 7 shows an intermediate mask data representing one pattern used inthe process for forming the first mask data.

FIG. 8 shows an intermediate mask data representing one pattern used inthe process for forming the first mask data.

FIG. 9 shows a figure representing the first mask data.

FIG. 10 shows a figure representing second mask data.

FIG. 11 shows figures indicating the relation between dummy patterns ina mask and patterns of dummy wiring layers in a semiconductor devicewhen the mask is formed based on the second mask data.

FIG. 12 shows a figure representing third mask data.

FIG. 13 shows a figure representing mask data.

FIGS. 14 (a)-14 (c) schematically show in cross section of asemiconductor device in different manufacturing steps.

FIGS. 15 (a) and 15 (b) schematically show in cross section of thesemiconductor device in different manufacturing steps.

FIG. 16 shows a plan view of wiring layers and dummy wiring layers in anembodiment sample.

FIG. 17 shows a plan view of wiring layers and dummy wiring layers in acomparison sample.

FIG. 18 schematically shows a cross section of a semiconductor devicehaving multiple wiring layers in a manufacturing step using aconventional multiple layer wiring technique.

FIG. 19 schematically shows a cross section of a semiconductor devicehaving multiple wiring layers in which dummy wiring layers are alsoformed.

DESCRIPTION OF PREFERRED EMBODIMENTS

Preferred embodiments of the present invention will be described belowwith reference to the accompanying drawings.

Semiconductor devices in accordance with embodiments of the presentinvention will be described below. FIG. 1 illustratively shows a planview of a semiconductor device. FIG. 2 illustratively shows across-sectional view taken along a line A-A of FIG. 1.

Referring to FIG. 2, a semiconductor device 1000 has a semiconductorsubstrate (for example, a silicon substrate) 10. Semiconductor elementssuch as MOSFETs, wiring layers and element isolation regions (not shown)are formed on a surface of the semiconductor substrate 10. A firstinterlayer dielectric layer 20 is formed over the semiconductorsubstrate 10

First wiring layers 30 and dummy wiring layers 32 are formed over thefirst interlayer dielectric layer 20. Depending on certain devicedesigns, some of the first wiring layers 30 may be closely formed in onearea and an isolated one of the first wiring layer 30 may be formedseparated from the other first wiring layers 30

Contact holes (not shown) may be formed in the first interlayerdielectric layer 20 at specified locations to connect semiconductorelements or wiring layers formed on the surface of the semiconductorsubstrate 10 to the first wiring layers 30. Contact layers (not shown)may be formed in the contact holes. The contact layers may be formedfrom, for example, tungsten plugs, aluminum alloy layers or copperlayers.

A second interlayer dielectric layer 40 is formed over the first wiringlayers 30 and the dummy wiring layers 32. Second wiring layers 50 areformed over the second interlayer dielectric layer 40.

A first contact hole 60 is formed in the second interlayer dielectriclayer 40. The first contact hole 60 is a connection aperture forconnecting the first wiring layers 30 and the second wiring layers 50. Afirst contact layer 62 is formed in the first contact hole 60. The firstcontact hole 62 is formed from, for example, a tungsten plug, analuminum alloy layer or a copper layer.

A second contact hole 70 is formed through the first interlayerdielectric layer 20 and the second interlayer dielectric layer 40. Thesecond contact hold 70 is a connection aperture for connecting asemiconductor element or a wiring layer formed on the surface of thesemiconductor substrate 10 to the second wiring layer 50. A secondcontact layer 72 is formed in the second contact hole 70. The secondcontact layer 72 is formed from, for example, a tungsten plug, analuminum alloy layer or a copper layer.

A pattern in plan view at a level where the first wiring layers 30 areformed is described below. FIG. 3 is a plan view of the level where thefirst wiring layers 30 are formed.

Prohibited areas 80 are set around the first wiring layers 30 and thesecond contact hole 70 (i.e., an area where the second contact layer 72is formed). It is noted that the first wiring layers 30 and the secondcontact hole 70 define wiring effective regions 90. Furthermore, thewiring effective regions 90 and the prohibited areas 80 definerestriction regions 100.

The prohibited areas 80 are regions that do not allow the dummy wiringlayers 32 to be generated. The width of the prohibited area 80 isdetermined in consideration of circuit design. For example, theprohibited area may have a width of 0.5-100 μm. When a semiconductordevice does not use circuits that use electromagnetic effects, such asinductors using wiring layers, the prohibited area 80 may preferablyhave a width of 0.5-20 μm, and more preferably 1-5 μm. It is noted thatthe prohibited areas 80 may or may not have the same width along theentire prohibited areas 80. For example, all of the prohibited areas 80around the first wiring layers 30 may have different widths.Alternatively, all of the prohibited areas 80 around the first wiringlayers 30 may have the same width.

Dummy wiring layers 32 are formed in areas other than the restrictionregions (including the wiring effective regions and the prohibitedareas) 100. In other words, the dummy wiring layers 32 are formed insuch a manner that the dummy wiring layers 32 do not overlap therestriction regions 100. More particularly, the dummy wiring layers 32that entirely or partially overlap the restriction regions 100 arecompletely excluded. Advantages derived from completely excluding thedummy wiring layers 32 that may partially overlap the restrictionregions 100 are described below.

The prohibited areas 80 are provided around the first wiring layers 32and the second contact hole 70 because of the following reasons.

(1) First Wiring Layer

Unless the prohibited areas 80 are provided around the first wiringlayers 30, dummy wiring layers 32 may be formed connected with the firstwiring layers 30. In this case, for example, the wirings become wide ornarrow in various places and thus have different resistance values atdifferent places. When the wirings have different resistance values atdifferent places, the designed wiring resistance values cannot beattained. As a result, device characteristics may vary. Also, due to theincreased area of the wirings, the wirings may be readilyshort-circuited.

(2) Second Contact Hole

Unless the prohibited area 80 is provided around the second contact hole70, a dummy wiring layer 32 may be formed in a region where the secondcontact hole 70 is formed. In this case, when the second interlayerdielectric layer 40 and the first interlayer dielectric layer 20 areetched to form the second contact hole 70, the dummy wiring layer 32 mayfunction as an etching stopper layer for the first interlayer dielectriclayer 20 such that the second contact hole 70 may not be formed.

Referring to FIG. 4, a disposition pattern of the dummy wiring layers 32is described below.

The dummy wiring layers 32 are located on first virtual linear lines L1.In one embodiment, for example, the dummy wiring layers 32 may be formedin a manner that centers of the dummy wiring layers 32 are located onthe first virtual linear lines L1.

The dummy wiring layers 32 are also formed in a manner to be located onsecond virtual linear lines L2. In one embodiment, for example, thedummy wiring layers 32 may be formed in a manner that centers of thedummy wiring layers 32 are located on the second virtual linear linesL2.

The dummy wiring layers 32 are disposed in a direction traversing afirst matrix direction (for example, a direction of rows or a directionof columns in a matrix) and also disposed in a direction traversing asecond matrix direction (for example, a direction of rows or a directionof columns in the matrix). The first matrix direction mayperpendicularly traverse the second matrix direction.

The first virtual linear lines L1 traverse the row direction. The firstvirtual linear lines L1 and the row direction define an angle θ1 that is2-40 degrees. Preferably, the angle θ1 is 15-25 degrees. Morepreferably, the angle θ1 is about 20 degrees. The “row direction” usedhere refers to one direction that is virtually defined in view of, forexample, the first wiring layers 30, the second contact hole 70, and theprohibited areas 80.

The second virtual linear lines L2 traverse the column direction. Thesecond virtual linear lines L2 and the column direction define an angleθ2 that is 2-40 degrees. Preferably, the angle θ2 is 15-25 degrees. Morepreferably, the angle θ2 is about 20 degrees. The “column direction”used here refers to one direction that is virtually defined, forexample, in consideration of the first wiring layers 30, the secondcontact hole 70, and the prohibited areas 80.

The first virtual linear lines L1 are defined in plurality. The firstvirtual linear lines L1 are defined to be separated from one another ata specified pitch. The first virtual linear lines L1 may be separatedfrom one another by any distance. However, in a preferred embodiment,adjacent ones of the first virtual linear lines L1 may be separated fromone another by a gap of, for example, about 1-16 μm, and more preferably2-5 μm. The second virtual linear lines L2 are defined in plurality. Thesecond virtual linear lines L2 are defined to be separated from oneanother at a specified pitch. The second virtual linear lines L2 may beseparated from one another by any distance. However, in a preferredembodiment, adjacent ones of the second virtual linear lines L2 may beseparated from one another by a gap of, for example, 1-16 μm, and morepreferably 2-5 μm.

Adjacent ones of the dummy wiring layers 32 disposed next to one anotheron each one of the first virtual linear lines L1 are mutually offset inthe column direction. The dummy wiring layers 32 may be offset in thecolumn direction by a width Y10. In one embodiment, the width Y10 is0.5-5 μm. In a preferred embodiment, the width Y10 is 0.5-2 μm, and morepreferably about 1 μm.

Adjacent ones of the dummy wiring layers 32 disposed next to one anotheron each one of the second virtual linear lines L2 are mutually offset inthe row direction. The dummy wiring layers 32 may be offset in the rowdirection by a width X10. In one embodiment, the width X10 is about0.5-5 μm. In a preferred embodiment, the width X10 is 0.5-2 μm, and morepreferably about 1 μm.

In a plan configuration, a ratio of an area occupied by the dummy wiringlayers 32 with respect to a unit area is not particularly limited.However, in a preferred embodiment, the area occupied by the dummywiring layers 32 in a unit area is 30-50%, and more preferably about40%. In one embodiment, the area occupied by the dummy wiring layers 32in a unit area may preferably be 30-50%, and more preferably about 40%.

The “unit area” used here is the minimum unit area that can be repeatedin an up-to-down direction and right-to-left direction to form theentire pattern. In one embodiment, a unit area is defined by a rectangleABCD shown in FIG. 4.

The configuration in plan view of the dummy wiring layer 32 is notparticularly limited. For example, the dummy wiring layer 32 may have apolygonal shape in plan view or a circular shape in plan view. In oneembodiment, the dummy wiring layer 32 may have a polygonal shape in planview. Preferably, the dummy wiring layer 32 may have a rectangular shapein plan view, and more preferably a square shape in plan view. When thedummy wiring layers 32 each have a generally square shape in plan view,the dummy wiring layers 32 can be more densely formed. For example, thedummy wiring layers 32 can be more securely formed even in an areaadjacent to a crossing area where prohibited areas cross each other atright angles. As a result, the dummy wiring layers 32 can be moreeffectively formed in an area adjacent to a prohibited area formed witha complex pattern (for example, a prohibited area around a wiring layerthat is formed with a complex pattern).

When the configuration in plan view of the dummy wiring layer 32 isgenerally square, the length T10 of each side of the dummy wiring layer32 is not particularly limited. However, for example, the length of eachside of the dummy wiring layer 32 may be 1-10 μm. Preferably, the lengthof each side of the dummy wiring layer 32 may be about 2 μm. When thelength T10 of each side of each of the dummy wiring layers 32 is about 1μm or greater, the amount of data for generating a mask, which is usedto form the dummy wiring layers 32, is prevented from substantiallyincreasing. When the length T10 of each side of each of the dummy wiringlayers 32 is 10 μm or shorter, the dummy wiring layers can be formed ina space between wiring layers that are separated from one another by atleast 10 μm, where step differences in an interlayer dielectric layerover the wiring layers are readily formed. Therefore, step differencesin the interlayer dielectric layer can be effectively eliminated.

When the configuration in plan view of the dummy wiring layer 32 isgenerally square, adjacent ones of the dummy wiring layers 32 disposednext to one another on the same one of the first virtual linear lines L1have sides S1 and S2 that partially oppose to one another. A gap G10between the partially opposing sides S1 and S2 is not particularlylimited to a specific range. However, the gap G10 may preferably be0.5-5 μm, and more preferably about 1 μm. Also, the gap G10 maypreferably be set shorter than the side length T10 of each of the dummywiring layers 32. More preferably, the gap G10 may be about a half ofthe side length T10 of each of the dummy wiring layers 32.

When the configuration in plan view of the dummy wiring layer 32 isgenerally square, adjacent ones of the dummy wiring layers 32 disposednext to one another on the same one of the second virtual linear linesL2 have sides S3 and S4 that partially oppose to one another. A gap G20between the partially opposing sides S3 and S4 is not particularlylimited to a specific range. However, the gap G20 may preferably be0.5-5 μm, and more preferably about 1 μm. Also, the gap G20 maypreferably be set shorter than the side length T10 of each of the dummywiring layers 32. More preferably, the gap G20 may be about a half ofthe side length T10 of each the dummy wiring layers 32.

When the configuration in plan view of the dummy wiring layer 32 isgenerally square, adjacent ones of the dummy wiring layers 32 disposednext to one another in the row direction are offset by a width Y10 inthe column direction. The width Y10 may preferably be about a half ofthe length of each side of the dummy wiring layer 32. Also, adjacentones of the dummy wiring layers 32 disposed next to one another in thecolumn direction are offset by a width X10 in the row direction. Thewidth X10 may preferably be about a half of the length of each edge ofthe dummy wiring layer 32.

The dummy wiring layers 32 having the configurations described aboveprovide at least the following effects. The effects obtained by theabove-described configurations of the dummy wiring layers 32 will bedescribed below with reference to FIG. 5.

(1) For example, let us consider one case in which a restriction region100 is provided in a manner shown in FIG. 5 (a). The restriction region100 includes a wiring effective region 90 and a prohibited area 80. Theprohibited area 80 extends in the row direction about the wiringeffective region 90. Let us consider one situation in which dummy wiringlayers 32 a in a lattice structure are formed in parallel with therestriction region 100. When the dummy wiring layers 32 a are formed ina lattice structure in parallel with the restriction region 40, and ifany one of the dummy wiring layers 32 a in one of the rows of thelattice overlaps the restriction region 100, all the other dummy wiringlayers 32 a in the same row overlap the restriction region 100. In orderto form dummy wiring layers 32 a adjacent to the restriction region 100while preventing the dummy wiring layers 32 a from overlapping therestriction region 100, the location of the dummy wiring layers 32 aneeds to be controlled. Such a control is technically difficult becauseit may cause a substantial increase in the amount of data for generatingmasks. On the other hand, when dummy wiring layers 32 a cannot be formedadjacent to the restriction region 100, the density of the dummy wiringlayers 32 a formed in an area adjacent to the restriction region 100becomes insufficient.

However, in accordance with the embodiments of the present invention, asshown in FIG. 5 (b), the dummy wiring layers 32 are disposed on thefirst virtual linear lines L1 that extend in a direction traversing therow direction. In other words, adjacent ones of the dummy wiring layers32 disposed next to one another on the same one of the first virtuallinear lines L1 are mutually offset in the column direction. As aresult, even when one of the dummy wiring layers 32 disposed on one ofthe first virtual linear lines L1 overlaps the restriction region 100,the next one of the dummy wiring layers 32 on the same first virtuallinear line L1 can be disposed without overlapping the restrictionregion 100. As a result, the dummy wiring layers 32 a can be securelyformed in an area adjacent to the restriction region 100 withoutsubstantially controlling the locations where the dummy wiring layer 32are formed.

Also, in accordance with the embodiments of the present invention, thedummy wiring layers 32 are disposed on the second virtual linear linesL2 that extend in a direction traversing the column direction. In otherwords, adjacent ones of the dummy wiring layers 32 disposed next to oneanother on the same one of the second virtual linear lines L2 aremutually off set in the row direction. As a result, even when one of thedummy wiring layers 32 disposed on one of the second virtual linearlines L2 overlaps the restriction region 100, the next one of the dummywiring layers 32 on the same second virtual linear line L2 can bedisposed without overlapping the restriction region 100. Accordingly,the dummy wiring layers 32 can be securely formed in areas adjacent tothe restriction region 100 that extends in the column direction.

(2) In the semiconductor device in accordance with the embodiments ofthe present invention, dummy wiring layers 32 that partially overlap arestriction region 100 are entirely eliminated. As a result, thefollowing effects are obtained

If dummy wiring layers 32 partially overlap a restriction region 100,portions (hatched areas) 32 b of the dummy wiring layers 32 do notoverlap the restriction region 100. The portions 32 b are hereafterreferred to as “hangover dummy wiring layers”. The hangover dummy wiringlayer 32 b has a shape in plan view that lacks a portion of the planshape of the original dummy wiring layer 32. In other words, thehangover dummy wiring layer 32 b has a smaller plan area compared to aplan area of the original dummy wiring layer 32. When the hangover dummywiring layer 32 b is extremely small in plan area (for example, when itis smaller than the resolution limit or the design rule), the followingproblems may occur.

(a) A resist layer to define the hangover dummy wiring layers 32 b isdifficult to form, and pattern skipping of the pattern for the hangoverdummy wiring layers 32 b occurs. (b) Even if a resist layer to definethe hangover dummy wiring layers 32 b is formed, the resist layer mayfall. The fallen resist layer becomes dusts in an etching step to formthe first wiring layers 30, and therefore deteriorates the etching step.(c) Convex portions of the hangover dummy wiring layers 32 b are verynarrow, and therefore may break in a washing step to be conducted afterthe wiring layers are patterned. The broken convex portions becomeforeign particles that may remain on the surface of the substrate. (d)If the foreign particles on the surface enter a dielectric layer, wiringlayers may become short-circuited.

In accordance with the embodiments of the present invention, anyhangover dummy wiring layers 32 b are not formed. As a result, theoccurrence of the problems described above is securely prevented.

One example of a method for generating mask data is described below. Themask data is used for forming first wiring layers and dummy wiringlayers. The mask data can be generated using a computer. FIG. 13 shows apattern representing a mask data set.

First, data for a first mask is generated. FIG. 9 shows a patternrepresenting first mask data 200. Restriction region patterns 242 thatdefine restriction regions are set in the first mask data 200. In oneembodiment, the first mask data 200 is formed in a manner describedbelow. FIGS. 6-8 show steps of forming the first mask data that includeintermediate mask data sets.

Initially, first and second intermediate mask data 210 and 220, whichrepresent regions shown in FIGS. 6 (a) and 6 (b), respectively, areprepared.

Wiring patterns 212 are defined in the first intermediate mask data 210in a manner shown in FIG. 6 (a). The wiring patterns 212 define firstwiring layers. A second contact hole pattern 222 is defined in thesecond intermediate mask data 220 in a manner shown in FIG. 6 (b). Thesecond contact hole pattern 222 defines a second contact hole.

Then, a logical sum of the first and second intermediate mask data 210and 220 is made to obtain third intermediate mask data 230 shown in FIG.7. In other words, the hatched regions 212 and 222 of the first andsecond intermediate mask data 210 and 220 are added to define wiringeffective region patterns 232 in the third intermediate mask data 230.The wiring effective region patterns 232 define wiring effectiveregions.

Then, the wiring effective region patterns 232 are expanded by aspecified width to obtain fourth intermediate mask data 240 shown inFIG. 8. In other words, prohibited area patterns 244 are added aroundthe wiring effective region patterns 232 to set the restriction regionpatterns 242. The prohibited area patterns 244 define prohibited areas.The restriction region patterns 222 define restriction regions.

Then, the fourth intermediate mask data 240 is diagrammatically reversedto obtain the first mask data 200 shown in FIG. 9. More particularly,the hatched regions in the fourth intermediate mask data 240 are changedto blank regions, and the blank regions in the fourth intermediate maskdata 240 are replaced with hatched regions, to generate the first maskdata 200.

Next, second mask data 300 is formed. FIG. 10 shows a patternrepresenting the second mask data 300. Dummy patterns 310 are defined inthe second mask data 300. The dummy patterns 310 correspond to thepatterns of the above-described dummy wiring layers 32 and thus definethe dummy wiring layers 32. In other words, the dummy patterns 310 andplacement patterns of the dummy wiring layers 32 are identical orapproximate to one another. More particularly, as shown in FIG. 11, whena mask 600 having dummy patterns 610 is formed based on the second maskdata 300, the dummy patterns 610 of the mask 600 correspond to thepatterns of the dummy wiring layers 32 to be formed in a semiconductordevice 700.

In a preferred embodiment, the dummy patterns 310 are disposed in thefollowing manner.

The dummy patterns 310 are formed in a manner to be located on firstvirtual linear lines L10. The dummy patterns 310 can be formed in amanner that centers of the dummy patterns 310 are located on the firstvirtual linear lines L10. Also, the dummy patterns 310 can be formed ina manner that portions other than the centers of the dummy patterns 310are located on the first virtual linear lines L10. In other words, thedummy patterns 310 are accepted as long as they are located on the firstvirtual linear lines L10.

The dummy patterns 310 are formed in a manner to be located on secondvirtual linear lines L20. The dummy patterns 310 may be formed in amanner that centers of the dummy patterns 310 are located on the secondvirtual linear lines L20. Also, the dummy patterns 310 may be formed ina manner that portions other than the centers of the dummy patterns 310are located on the second virtual linear lines L20. In other words, thedummy patterns 310 are accepted as long as they are located on thesecond virtual linear lines L20.

The first virtual linear lines L10 traverse the row direction. The firstvirtual linear lines L10 and the row direction define an angle θ10 thatis 2-40 degrees. Preferably, the angle θ10 is 15-25 degrees. Morepreferably, the angle θ10 is about 20 degrees. The “row direction” usedhere refers to one direction that is virtually defined in view of, forexample, the wiring patterns, the second contact hole pattern, and theprohibited area patterns.

The second virtual linear lines L20 traverse the column direction. Thesecond virtual linear lines L20 and the column direction define an angleθ20 that is 2-40 degrees. Preferably, the angle θ20 is 15-25 degrees.More preferably, the angle θ20 is about 20 degrees. The “columndirection” used here refers to one direction that perpendicularlytraverses the row direction and is virtually defined in view of, forexample, the wiring patterns, the second contact hole pattern, and theprohibited area patterns.

The first virtual linear lines L10 are defined in plurality. The firstvirtual linear lines L1 are defined to be separated from one another ata specified pitch. The second virtual linear lines L2 are defined inplurality. The second virtual linear lines L2 are defined to beseparated from one another at a specified pitch. A gap D10 betweenadjacent ones of the first virtual linear lines L10 is set such that agap D1 between adjacent ones of the first virtual linear lines L1 in asemiconductor device acquires a designed amount (see FIG. 11). Also, agap D20 between adjacent ones of the second virtual linear lines L20 isset such that a gap D2 between adjacent ones of the second virtuallinear lines L2 in the semiconductor device acquires a designed amount(see FIG. 11).

It is noted that the second mask data 300 can be formed before the firstmask data 200 is formed.

Next, the first mask data 200 and the second mask data 300 are mixed toform a third mask data 400. FIG. 12 shows a pattern representing thethird mask data 400. For example, the first and second mask data 200 and300 can be mixed in the following manner. Common areas of the hatchedregions in the first mask data 200 and the dummy patterns (hatchedregions) 310 of the second mask data 300 are extracted. In other words,the dummy patterns 310 that overlap the restriction region patterns 242are excluded. It is noted that the dummy patterns 312 that partiallyoverlap the restriction region patterns 242 are also entirely excluded.

Then, a logical sum of the third mask data 400 and the firstintermediate mask data 210 is obtained. In other words, the wiringpatterns (hatched regions) 212 of the first intermediate mask data 210are added to the third mask data 400. As a result, mask data 500 shownin FIG. 13 is obtained for a mask that is used to form the first wiringlayers and the dummy wiring layers.

When a positive type resist is used for patterning the wiring layers,the hatched regions of the mask data 500 represent shading portions ofthe mask (for example, chrome patterns). When a negative type resist isused, regions other than the hatched regions (i.e., blank regions) ofthe mask data 500 represent shading portions of the mask (for example,chrome patterns).

The mask data 500 thus obtained can be recorded in a computer readablerecording media if required. Also, a mask that is used to form the firstwiring layers and the dummy wiring layers can be obtained based on themask data 500.

In the method for generating mask data in accordance with theembodiments of the present invention, the dummy patterns 310 correspondto placement patterns of the dummy wiring layers 32 as described above.As a result, for the same reasons described above in conjunction withthe effects of the semiconductor device in accordance with theembodiment of the present invention, the dummy patterns 310 can besecurely generated in areas adjacent to the restriction regions 24without controlling placement positions of the dummy patterns 310. Inother words, the dummy patterns 310 can be automatically generated inareas adjacent to the restriction region patterns 242. As a result, whena mask is obtained by the method for generating mask data in accordancewith the embodiments of the present invention, and such a mask is usedto form dummy wiring layers, the dummy wiring layers can be securelyformed in areas adjacent to restriction regions. Accordingly, when adielectric layer formed over the wiring layers is polished, thepolishing pressure is securely distributed on the dummy wiring layers inareas adjacent to the restriction regions.

Also, the dummy patterns 310 that at least partially overlap therestriction region patterns 242 are entirely excluded. As a result, thegeneration of pattern skipping of patterns of dummy wiring layers can besecurely prevented.

Furthermore, since the dummy patterns 310 can be securely set in areasadjacent to the restriction region patterns 242, the dummy patterns 310can also be securely set in regions where gaps between adjacentrestriction region patterns 242 are narrow.

In accordance with the embodiments of the present invention, the step ofgenerating the first mask data 200 includes the step of diagrammaticallyreversing the fourth intermediate mask data 240. However, depending onsoftware used for generating mask data, the step of diagrammaticallyreversing the fourth intermediate mask data 240 may not necessarily beincluded.

Next, a method for manufacturing a semiconductor device in accordancewith an embodiment of the present invention will be described. FIGS. 14and 15 schematically show cross sections of a semiconductor device inmanufacturing process steps.

(1) Referring to FIG. 14 (a), semiconductor elements (for example,MOSFETs), wiring layers, and element isolation regions (not shown) areformed over a silicon substrate 10 by a known method.

Then, a first interlayer dielectric layer 20 is formed over thesemiconductor substrate 10. The first interlayer dielectric layer 20 maybe formed in the same manner as a second interlayer dielectric layer 40(to be described below) is formed. The thickness of the first interlayerdielectric layer 20 is not limited to a specific range. For example, thethickness of the first interlayer dielectric layer 20 is about 300nm-1000 nm. The first interlayer dielectric layer 20 can be planarizedby a chemical-mechanical polishing (CMP) method depending onrequirements.

Contact holes (not shown) are formed in the first interlayer dielectriclayer 20. For example, the contact holes are formed by an anisotropicreactive ion etching. Contact layers (not shown) are formed in thecontact holes by a known method. The contact layers are formed from, forexample, tungsten plugs or aluminum alloy layers.

A conductive layer 36 is formed over the first interlayer dielectriclayer 20. The conductive layer 36 is not limited to a specific material.For example, an alloy of aluminum and copper, titanium nitride, titaniumcan be used for the conductive layer 36. The conductive layer 36 may beformed by an appropriate method, for example, a sputtering method. Thethickness of the conductive layer 36 may be appropriately selecteddepending on device designs. For example, the thickness of theconductive layer 36 is about 50-700 nm.

Next, a resist layer R1 is formed over the conductive layer 36.

(2) Then, the resist layer R1 is exposed and developed to therebypattern the resist layer R1 as shown in FIG. 14 (b). A mask that is usedfor exposing the resist layer R1 is manufactured based on the mask dataobtained by the method for generating mask data in accordance with thepresent invention. It is noted that an area above a forming region wherea second contact hole 70 is to be formed is not opened.

(3) Then, as shown in FIG. 14 (c), the conductive layer 36 is etchedusing the resist layer R1 to thereby form first wiring layers 30 anddummy wiring layers 32 having specified patterns.

Then, as shown in FIG. 15 (a), a dielectric layer 42 is formed over thefirst interlayer dielectric layer 20, the first wiring layers 30 and thedummy wiring layers 32. The dielectric layer 42 may be formed from, forexample, silicon oxide. When the dielectric layer 42 is formed fromsilicon oxide, the silicon oxide may contain phosphorous, boron or thelike. The dielectric layer 42 may be formed by, for example, a CVDmethod, a coating method. The thickness of the dielectric layer 42 isnot limited to a specific range or value. For example, the thickness ofthe dielectric layer 42 is about 500-2000 nm.

Then, the dielectric layer 42 is polished by a CMP method to planarizethe dielectric layer 42 to form a second interlayer dielectric layer 40shown in FIG. 15 (b). The thickness of the resultant second interlayerdielectric layer 40 may vary depending on device designs, and may be,for example, 200-600 nm. The following effects are achieved when thedielectric layer 42 is planarized. Namely, the dummy wiring layers 32are formed with the placement pattern that is described above inconnection with the semiconductor device in accordance with theembodiment of the present invention. Accordingly, the dummy wiringlayers 32 are securely formed in areas adjacent to the restrictionregions. As a result, the polishing pressure can be more securelydistributed over the dummy wiring layers 32 to the extent that the dummywiring layers 32 are more securely formed in areas adjacent to therestriction regions. Thus, the polishing pressure can be betterprevented from concentrating on the isolated first wiring layer 30, andtherefore the dielectric layer 42 over the isolated first wiring layer30 can be better prevented from being excessively cut. As a result, thesecond interlayer dielectric layer 40 can be better planarized.

Then, as shown in FIG. 2, second contact holes 70 (only one contact holeis shown in the figure) are formed in the first and second interlayerdielectric layers 20 and 40 at specified regions by photolithography andetching methods. Then, second contact layers 72 are formed in the secondcontact holes 70.

Then, first contact holes 60 (only one contact hole is shown in thefigure) are formed in the second interlayer dielectric layer 40 atspecified regions by photolithography and etching methods. Then, firstcontact layers 62 are formed in the first contact holes 60.

Next, a conductive layer is formed over the second interlayer dielectriclayer 40, and the conductive layer is patterned to form second wiringlayers 50, whereby a semiconductor device 1000 is completed.

Effects of the method for manufacturing semiconductor devices inaccordance with the embodiment of the present invention will bedescribed.

By the method for manufacturing a semiconductor device in accordancewith the embodiment of the present invention, the dummy wiring layers 32are formed with the same pattern of the dummy wiring layers 32 describedabove in conjunction with the structure of the semiconductor device.Accordingly, the dummy wiring layers 32 are securely formed in areasadjacent to the restriction regions. As a result, when the dielectriclayer 42 is polished, the dielectric layer 42 over the isolated wiringlayer 30 can be better prevented from being excessively cut. Thus, thesecond interlayer dielectric layer 40 can have a more uniform thickness.

Experiments are conducted to show how patterns of dummy wiring layerschange the formation of the dummy wiring layers between wiring effectiveregions.

Conditions for embodiment samples will be described below.

(1) In accordance with one embodiment of the present invention, in anembodiment sample, placement patterns of dummy wiring layers are madeaccording to the following rule:

(a) An angle between the first virtual linear lines and the row line isabout 18.4 degrees.

(b) A gap between the adjacent first virtual linear lines is about 3.2μm.

(c) An angle between the second virtual linear lines and the column lineis about 18.4 degrees.

(d) A gap between the adjacent second virtual linear lines is about 3.2μm.

(e) A ratio of an area of the dummy wiring layers occupied in a unitarea is 40%.

(f) A shape of each of the dummy wiring layers in plan view is square.

(g) Each side of each of the dummy wiring layers in plan view has alength of 2 μm.

(h) A gap between opposing sides of adjacent ones of the dummy wiringlayers disposed next to one another on the same one of the first virtuallinear lines is 1 μm.

(i) A gap between opposing sides of adjacent ones of the dummy wiringlayers disposed next to one another on the same one of the secondvirtual linear lines is 1 μm.

(j) An offset width in the column direction between opposing sides ofadjacent ones of the dummy wiring layers disposed next to one another onthe same one of the first virtual linear lines is 1 μm.

(k) An offset width in the row direction between opposing sides ofadjacent ones of the dummy wiring layers disposed next to one another onthe same one of the second virtual linear lines is 1 μm.

(l) The dummy wiring layers are formed such that their centers arelocated on the first virtual linear lines.

(m) The dummy wiring layers are formed such that their centers arelocated on the second virtual linear lines.

(n) Any dummy wiring layers that may entirely or partially overlaprestriction regions 100 (including dummy wiring layers connecting torestriction regions) are excluded.

(2) The restriction regions 100 include wiring effective regions (wiringlayers) 90 and prohibited areas 80 provided around the wiring effectiveregions (wiring layers) 90.

(3) The width of each of the prohibited areas 80 is 1 μm.

A region A10 and a region B10 are set. In the region A10, a gap betweenadjacent ones of the wiring effective regions (i.e., the wiring layers)90 is 10 μm. In the region B10, a gap between adjacent ones of thewiring effective regions (i.e., the wiring layers) 90 is 6 μm.

Conditions for comparison samples will be described below.

(1) In a comparison sample, dummy wiring layers are disposed in the formof a lattice. More particularly, the dummy wiring layers are disposedaccording to the following rule:

(a) A gap between adjacent ones of the dummy wiring layers disposed nextto one another in the row direction is 1 μm.

(b) A gap between adjacent ones of the dummy wiring layers disposed nextto one another in the column direction is 1 μm.

(c) A shape of each of the dummy wiring layers in plan view is square.

(d) Each side of each of the dummy wiring layers in plan view has alength of 2 μm.

(e) Any dummy wiring layers that may entirely or partially overlaprestriction regions 100 (including dummy wiring layers connecting to therestriction regions) are entirely excluded.

(2) The restriction regions 100 include wiring effective regions 90 andprohibited areas 80 provided around the wiring effective regions 90.

(3) The width of each of the prohibited areas 80 is 1 μm.

(4) The same patterns as those of the embodiment samples are used forpatterns of the wiring effective regions (i.e., the wiring layers) 90. Aregion of the comparison sample corresponding to the region A10 of theembodiment sample is presented as B10, and a region of the comparisonsample corresponding to the region A20 of the embodiment sample ispresented as B20.

Comparison results are shown in FIGS. 16 and 17. FIG. 16 shows a planview of wiring effective regions (wiring layers) and dummy wiring layersof the embodiment sample of the present invention. FIG. 17 shows a planview of wiring effective regions (wiring layers) and dummy wiring layersof the comparison sample. In the figures, squares shown by solid linesindicate dummy wiring layers that are actually formed, and squares shownby broken lines indicate virtual dummy wiring layers that are excluded.

In the comparison example shown in FIG. 17, only one line of the dummywiring layers is formed in the region A20. In other words, dummy wiringlayers are not formed adjacent to the restriction regions 100. Incontrast, as shown in FIG. 16, in accordance with the embodiment of thepresent invention, the dummy wiring layers are securely formed in theregion A10 in areas adjacent to the restriction regions 100.

Also, in the embodiment sample of the present invention shown in FIG.16, the dummy wiring layers are formed in an area where the gap betweenthe wiring effective regions (i.e., the wiring layers) is narrow (seethe region B10). In contrast, in the comparison example shown in FIG.17, dummy wiring layers are not formed in an area where the gap betweenthe wiring effective regions (i.e., the wiring layers) is narrow (seethe region B20).

It is understood from the above that the embodiment sample of thepresent invention more securely form dummy wiring layers adjacent torestriction regions 100 compared to the comparison example.

The present invention is not limited to the embodiments described above,and many modifications can be made within the scope of the subjectmatter of the present invention.

(1) In the embodiments described above, the dummy wiring layers 32 areformed in a manner that their centers are disposed on the first virtuallinear lines L1. However, the dummy wiring layers 32 may be formed in amanner that portions other than their centers are disposed on the firstvirtual linear lines L1. In other words, it is acceptable if the dummywiring layers 32 may be disposed on the first virtual linear lines L1.

(2) In the embodiments described above, the dummy wiring layers 32 areformed in a manner that their centers are disposed on the second virtuallinear lines L2. However, the dummy wiring layers 32 may be formed in amanner that portions other than the centers of the dummy wiring layers32 are disposed on the second virtual linear lines L2. In other words,it is acceptable if the dummy wiring layers 32 may be disposed on thesecond virtual linear lines L2.

(3) In the embodiments described above, the dummy wiring layers 32 areformed over the first interlayer dielectric layer 20. However, thepresent invention is not limited to this embodiment. The dummy wiringlayers 32 may be formed over a second interlayer dielectric layer orabove.

(4) In the embodiments described above, the second contact hole 70formed in the first interlayer dielectric layer 20 and the secondinterlayer dielectric layer 40 defines a wiring effective region.However, the present invention is not limited to this embodiment. Forcontact holes that pass through a plurality of interlayer dielectriclayers, wiring effective regions for the contact holes may be defined ina wiring layer provided between the plurality of interlayer dielectriclayers. In other words, for example, when an upper wiring layer isformed in a layer above dummy wiring layers, another lower wiring layeris formed in a layer below the dummy wiring layers, and a contact holefor connecting the upper wiring layer and the lower wring layer, aregion where the contact hole is formed is defined as a wiring effectiveregion at the level where the dummy wiring layers are formed.

While the description above refers to particular embodiments of thepresent invention, it will be understood that many modifications may bemade without departing from the spirit thereof. The accompanying claimsare intended to cover such modifications as would fall within the truescope and spirit of the present invention.

The presently disclosed embodiments are therefore to be considered inall respects as illustrative and not restrictive, the scope of theinvention being indicated by the appended claims, rather than theforegoing description, and all changes which come within the meaning andrange of equivalency of the claims are therefore intended to be embracedtherein.

What is claimed is:
 1. A semiconductor device comprising: a plurality offirst wirings extending in a first direction, the plurality of firstwirings are arranged adjacent to each other in a second direction on alayer level; a second wiring that is apart from the plurality of firstwirings in the second direction on the layer level; and a plurality ofdummy wirings arranged between the plurality of first wirings and thesecond wiring on the layer level, wherein the plurality of dummy wiringsare arranged at a plurality of crossing points between first virtuallinear lines extending in a third direction and second virtual linearlines extending in a fourth direction, wherein: the third direction andthe fourth direction are neither parallel nor orthogonal to the firstdirection and the second direction, the plurality of dummy wiringshaving: a first dummy wiring; a second dummy wiring; and a third dummywiring, wherein centers of the second dummy wiring and the third dummywiring are nearest to a center of the first dummy wiring relative toothers of the plurality of dummy wirings, and the respective centers ofthe first dummy wiring, the second dummy wiring, and the third dummywiring are aligned on a third virtual linear line extending in a fifthdirection neither parallel to nor perpendicular to the first directionand the second direction, the plurality of dummy wirings aresquare-shaped in a plan view, a distance between the first dummy wiringand the second dummy wiring is smaller than a length of each side of thefirst dummy wiring, and a distance between the first dummy wiring andthe third dummy wiring is smaller than the length of each side of thefirst dummy wiring.
 2. The semiconductor device according to claim 1,wherein an angle between the third virtual linear line and the firstdirection is between 15 and 25° and an angle between a fourth virtuallinear line and the second direction is between 15 and 25°.
 3. Thesemiconductor device according to claim 1, wherein an angle between thethird virtual linear line and the first direction is between 2 and 40°,and an angle between a fourth virtual linear line and the seconddirection is between 2 and 40°.
 4. The semiconductor device of accordingto claim 1, wherein each distance between adjacent ones of the pluralityof dummy wirings is about half of a length of each side of each of theplurality of dummy wirings.
 5. The semiconductor device according toclaim 1, wherein a plan area of layers of the dummy wirings occupies aunit plan area at a rate of 30-50%.
 6. The semiconductor deviceaccording to claim 1, wherein an angle between the third virtual linearline and the first direction is between 2 and 40° and the dummy wiringsare formed from an alloy of aluminum and copper.
 7. The semiconductordevice according to claim 1, wherein an angle between the third virtuallinear line and the first direction is between 2 and 40°, an anglebetween the fourth virtual linear line and the second direction isbetween 2 and 40°, a via plug connects a wiring on another layer levelwith the plurality of first wirings or the second wiring on the layerlevel, and the via plug is made of tungsten.
 8. The semiconductor deviceaccording to claim 7, wherein the distance between the first dummywiring and the second dummy wiring is in a range of 0.5 to 5.0 μm. 9.The semiconductor device according to claim 7, wherein the distancebetween the first dummy wiring and the second dummy wiring isapproximately 1.0 μm and the distance between the first dummy wiring andthe third dummy wiring is approximately 1.0 μm.
 10. A semiconductordevice comprising: a plurality of first wirings extending in a firstdirection, the plurality of first wirings are arranged adjacent to eachother in a second direction on a layer level; a second wiring that isapart from the plurality of first wirings in the second direction on thelayer level; and a plurality of dummy wirings arranged between theplurality of first wirings and the second wiring on the layer level,wherein the plurality of dummy wirings are arranged at a plurality ofcrossing points between first virtual linear lines extending in a thirddirection and second virtual linear lines extending in a fourthdirection, wherein: the third direction and the fourth direction areneither parallel nor orthogonal to the first direction and the seconddirection, the plurality of dummy wirings having: a first dummy wiring;a second dummy wiring; and a third dummy wiring, wherein centers of thesecond dummy wiring and the third dummy wiring are nearest to a centerof the first dummy wiring relative to others of the plurality of dummywirings, wherein the respective centers of the first dummy wiring, thesecond dummy wiring, and the third dummy wiring are aligned on a thirdvirtual linear line extending in a fifth direction neither parallel tonor perpendicular to the first direction and the second direction,wherein the dummy wirings have a polygonal shape and rotationalsymmetries through 90 degrees about respective centers of the dummywirings, and wherein an angle between the third virtual linear line andthe first direction is between 2 and40°.
 11. The semiconductor deviceaccording to claim 10, wherein the dummy wirings are formed from analloy of aluminum and copper.
 12. The semiconductor device according toclaim 10, further comprising a via plug connecting a wiring on anotherlayer level to the first or second wiring on the layer level, whereinthe via plug is made of tungsten.